1. Field of the Invention
The present invention relates to surgical staplers. More particularly, it relates to a surgical stapler having a tissue spacer that aligns, spaces and supports the tissue margins of a wound during a stapling procedure to avoiding overriding or crushing of tissues by the surgical staple upon closure.
2. Prior Art
Surgical staplers, also known as skin staplers, are surgical stapling instruments for implanting and forming surgical staples in the skin or fascia of a patient to close a wound or incision. The typical surgical stapler comprises an elongated body having a forward portion and a rearward portion serving as a handle portion. The forward portion of the instrument body houses a staple pusher or driver attached to a staple driver actuator and a return spring for the staple driver actuator. A surgical staple magazine assembly is affixed to the lower edges of the instrument body forward portion. An anvil plate, supporting a row of surgical staples, is located within the magazine assembly. The anvil plate terminates at its forward end in a coextensive anvil surface. The magazine assembly contains a feeder assembly to constantly urge the row of staples toward the anvil surface to locate the forwardmost staple of the row thereon to be implanted and formed thereabout by the driver and to disengage a formed staple therefrom. The magazine assembly also provides a channel for the lower end of the staple driver and a staple retaining surface to minimize bending of the staple crown during the staple forming operation. The staple driver is shiftable between a retracted position and a staple forming position by means of a trigger pivotally mounted to the instrument body forward portion and operatively connected to the staple driver actuator.
In these devices, the staple pusher or driver having an end with an inverted generally U-shaped recess advances a surgical staple, which is preformed in a broad-based, square-cornered U shape, downwardly toward the anvil plate. The base of the inverted U-shaped recess in the staple pusher or driver is broader or wider than the anvil plate, but not as broad or wide as the base of the U-shaped staple. When the staple reaches the anvil, the staple pusher or driver causes the staple to bend around the anvil into a closed, square-cornered C shape (known as forming the staple). As this is taking place, the ends or tines of the staple enter the tissue on the respective opposite sides of the incision or wound and draw the tissue together. When the staple has been fully formed, the staple pusher or driver is retracted and the stapler is removed. The staple remains in the tissue to hold it together during healing.
There are several patents that disclose surgical staplers or skin staplers with various features and a wide variety of feeding mechanisms to deliver each staple to the delivery point where the staple is deformed during implantation into the skin and/or tissue. See, for example: U.S. Pat. Nos. 4,179,057; 4,582,237; 5,038,991; and 5,937,951.
In addition to the surgical staplers and skin staplers identified above, there are other known skin approximator apparatus and combination surgical stapler and skin approximators for surgically stapling wounds.
U.S. Pat. No. 4,506,669 to Blake discloses a skin approximator consisting of a hinged device having two opposite disposed arms, each with a pair of barbs for engaging the skin on the opposite sides of the wound. Once engaged, the tissues are drawn together through a hinged motion of the arm thus allowing closure of the wound with a surgical staple placed in the conventional manner.
U.S. Pat. No. 5,423,856 to Green discloses an apparatus and method for surgical stapling comprising of a pair of side pointed jaws for engaging the tissues. The jaws are movable towards and away from each other. Once the tissues are approximated, the tissues are closed with a folding staple in the conventional manner.
U.S. Pat. No. 5,893,855 to Jacobs discloses an apparatus and method for the surgical stapling of body tissues. The invention consists of a surgical apparatus having a retractable approximation device that enables the operator to temporarily close the wound while positioning the staple injection port over the closed wound. Activation of the stapler stabs the staple tines into the tissues adjacent to the closed wound and then closes the staple within the tissues. An alternate embodiment provides for the use of asymmetrical staples that allows the longer staple leg to be stabbed into the tissues and thus used as an approximator before inserting the shorter leg of the staple. The staple is then bent in the conventional manner to close the wound.
The above-described patents are directed toward the closure of a wound with staplers and cumbersome combination approximation devices for the approximation of the wound edges prior to the placement of the surgical staples.
Currently, the conventional commercially available and most widely used staplers do not utilize cumbersome approximation devices but rather rely on the skill of the surgeon to approximate the margins of the wound.
In the current method of surgical stapling using conventional staplers, the surgeon approximates the wound margins, the stapler is centered over the wound, and the stapler is activated. The staple tines are inserted into the tissues and the staple is then bent closed. The activation of the handle or trigger on the stapler either retracts a central movable anvil between the sides of the inverted U-shaped recess in the staple pusher or driver, or the inverted generally U-shaped recess is lowered toward the anvil plate causing the staple to bend around the anvil into a closed, square-cornered C shape.
In either case the amount of tissue enclosed between the pointed ends of the staples as they are placed in the tissues is dependent on the skill and experience of the surgeon. Staples are then placed sequentially along the wound to be closed.
The commonly accepted procedure is to manually approximate the wound margins prior to the staple insertion. If the tissue margins are closely approximated prior to the staples being placed, i.e. in common practice in contact with each other, there will be excessive tissue captured within the staple on closure.
The width of the anvil plate over which the staple is bent determines the final internal staple width. The width between the tines of the staple in its open (unbent) condition is usually about twice the width of the anvil plate over which the staple is bent. As the staple is bent around the anvil plate, the staple closes capturing all tissues caught between the staple tines, which results in about double the optimal quantity of tissue becoming encompassed within the staple on its closure.
Optimal wound margin spacing and alignment requires a very skilled surgeon who is capable of leaving a sufficient yet proper wound gap when placing the staples. Proper initial staple placement will assure accurate alignment of the tissues when the staple is subsequently closed. When too little tissue is enclosed, gaps result. The resultant dead spaces allow easy foreign matter and microbial invasion and also the collection of serum and blood, which provide an ideal medium for the growth of microorganisms that cause infection.
Conversely, when too much tissue is enclosed initially, closure causes tissue compression so that both wound healing and resultant cosmetic appearance are compromised. Several possible mechanical complications and consequences may result from enclosing too much tissue within the confines of the closed staples. With currently commercially available staplers, it is common to see longer wound closures exhibit a combination of such consequences.
The relative sharpness of the points of the staples as well as the relative angle at which the staples are placed greatly effect the end result. If the conventional stapler is held at an angle such that one side is held more tightly against the tissues, one end of the staple will more efficiently penetrate the tissues. The staple will be inserted at an angle and the wound margin first penetrated may be carried upward forcing it to override the opposing wound margin thus exposing raw tissue. The opposite wound margin may be forced underneath when the staple is closed. Tissue margin overlapping which results in the exposure of raw tissue is the most common imperfection seen in surgical closures. In that a surgeon will see the results of partial closure with the resultant overlapping, compensation is made resulting in overlapping of the alternate side. It is common to see wound closures with alternating raw tissue margins exposed.
The crushing apposition of unlike tissues retards healing by requiring the deposition of vast quantities of fibrous connective tissue to bridge the faults thus resulting in significant scarring. Additionally, crushing causes blood supply strangulation which compromises all healing.
Even when the conventional stapler is placed squarely across a wound with approximated tissue margins, the excessive tissue collected between the straight staple ends will be forced tightly together upon closing. This can result in either forcing both tissue margins to be turned outward exposing the raw margins, both being turned inward retarding healing, or the margins properly approximated yet crushed together. These three imperfections are not common because tissue strength and integrity usually forces the wound margin on one side to override the other.
Tensile strength of the tissues to be closed greatly affects healing time. The high tissue strength of skin and fascia provide excellent staple holding characteristics but their relatively limited blood supply limits the healing process. When tissue entrapment occurs within staples, blood supply can be severely compromised which additionally retards healing thus inviting tissue necrosis. At least some degree of necrosis occurs in all cases following staple crushing of tissues and the resultant ischemia. Healing is then compromised until collateral circulation forms and the healing processes established.
When too much tissue is enclosed within the confines of the staples so that tissue compression occurs, additional ischemia produced by the post surgical swelling compromises healing even further. Conversely when the tissue volume within the confines of the closed staple approximates the normal mass of tissue that would ordinarily be present, expected post surgical or post trauma swelling merely assures excellent tissue approximation between sequentially placed staples.
The present invention overcomes the above stated problems, and is distinguished over the prior art by a surgical stapler having a tissue spacer at its forward end. The spacer is inserted between lateral sides of a wound to be closed and holds the tissue on lateral sides of the wound apart while the tines of a staple are driven into the tissue margins and bent around the staple bending surface of the staple anvil to draw the tissue captured between the tines toward each other. The tissue spacer has a width greater than the width of the staple bending surface of the anvil and less than the distance between the tines of the staple in an unbent condition such that when inserted between lateral sides of the wound it will space the facing tissue margins or the wound apart a distance sufficient to provide a metered amount of tissue lateral sides of the wound that will be captured between the tines and drawn together as the tines are bent toward each other to close the wound without crushing or overlapping of the captured tissue.